Absorption refrigerating apparatus



March 25, 1935., m c 1,995,41@

ABSORPTION REFRIGERATING APPARATUS Filed Jan. 23. 1934 Edmund #zzmhm Patented Mar. 26, 193

E TE s PATENT OFFICE I ABsoar'rIoN nnriifi n g'rmo APQARATUS Edmund Altenkirch, Neuenhagen, near Berlin,

Germany,- assignor to-The Hoover Company, North Canton, Ohio, a corporation of Ohio 18 Claims. (Cl. 62119.3)

This invention relates to absorption refrigerat- The dome 11 of the boiler is connected to the causing the total pressure of these vessels to be,

about the same as that prevailing in the boiler and in the condenser, so as to render unnecessary, the use of pumps and expansion valves for maintaining', a diflerence in pressure between the evaporator and the condenser. In such apparatus,it is necessary, however, to circulate absorption liquid between the boiler and the absorber.

In accordance with the-present invention, it is proposed to so arrange and locate the various vessels of a continuous-absorption refrigerating unit that the absorption liquid circulates between the boiler and the absorber automatically as a result of the difierence in the specific weight of two columns of liquid, underthe influence of gravity. 7

The main object of the invention is therefore to provide a continuous absorption refrigerating apparatus in which absorption liquid is circulated without the use of a pump of any kind.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

The single figure'is a diagrammatic representation of a continuous absorption refrigerating apparatus showing the vertical arrangement and location of the various parts and which illustrates one type of apparatus capable of carrying out the principles ofthe present invention.

Referring to the drawing in detail, it will be seen that the apparatus consists of a boiler B,

or expeller, a condenser C, an evaporator E, absorber A and a jet J as essential elements, these parts being connected by various conduits as shown tomake up the complete refrigerating system.

The boiler 13 may be .of the usual construction consisting of a horizontal closed cylinder of seamless steel tubing or the like as indicated at 10 and provided with a dome of the same material as indicated at 11. Heat may be supplied to the boiler by means of the electric cartridge heaters 12 located in'a horizontal heating tube 13.

opposite ends;

31 are connected to the lower surface of the abcondenser C by means of a conduit 14. The condenser C is shown as consisting of merely a coil of pipe located in a water cooling jacket or vessel 15 through which water may be circulated by 5 means of the conduits l6 and 1'7. The lower end of the condenser is connected to a vertically extending pipe 18 which passes downwardly to the lower portion of the unit where it enters a vertical cylinder or tube 19 at a point near the evaporator 10 and passes to a point just a little short of the bottom of the tube 19. The upper'end of the tube 19 is connected to the top of the evaporator by means of the short horizontal pipe 21, while the lower end of the tube 19 is connected to a small 15 auxiliary boiler 22 which is used to supply gas to the jet J as explained hereinafter.

The evaporator E is of a known type consisting merely of a vertical cylinder closed at the top and bottom and provided with a number of bafile 20 plates as indicated in 24. An inert or non absorbable gas, as for example air or hydrogen is circulated between the evaporator E and the absorber A by means of the gas conduit 26. The

gas leaves the top of the evaporator through 25 the vertical cylinder of the conduit 26 and is then impelled tugh the horizontal portion of this conduit by the jet J and into the absorber. Gas returning to the evaporator from the absorber enters at the lower. portion of the evaporator through the conduit 25.

In the apparatus shown the absorber A consists merely of a horizontal closed vessel. It is provided with a jacket 27 through which cooling water may be circulated by means of the conduits 28 and 29. The gas conduits 25 and 26 are connected to the upper surface of the absorber at Absorption liquid conduits 30 and sorber A at the opposite ends thereof. The conduits 30 and 31 extend downwardly below the absorber to provide U bends and then pass upwardly to the boiler B being connected to the lower surface of the oppositeend thereof. The absorption liquidconduits 30 and 31 may be in heat exchange relation over a portion of their length as indicated at 32. One of these conduits, as for example the conduit 31 may have a portion of its length formed into a coil as indicated at 33 and this coil may be provided with a jacket 34 through which cooling water may be circulated to pre-cool the absorption liquid entering the absorber.

For circulating the inert gas in the evaporator and the absorber, the jet J is provided, as mentioned above. This jet may consist merely of a small nozzle discharging into a restriction or venturi in the gas pipe 26. Gas is supplied to the jet through a conduit 35 connected to a small gas separation chamber 36 .which is in turn connected by conduits 37 and 38 to the small auxiliary boiler 23. The pipe 37 passes from the upper portion of the boiler 23 to the upper portion of the vessel 36, while the pipe 38 is connected to the lower portion of vessel 36 and to the lower portion of the auxiliary boiler 23. With this arrangement there is no danger of liquid passing to the jet J even though the liquid level in the auxiliary boiler 23 fluctuates considerably. The pressure difference necessary for causing gas to flow through the jet J is provided by means of the liquid column in the tube 19.

. For draining away any liquid which has not evaporated in the evaporator E, the drain conduit 39 is provided, this conduit being connected tothe liquid pipe 30.

Itwill be seen that in the arrangement shown the evaporator and the absorber are located some distance below the boiler and the condenser. This may be a decided advantage in some installations where it is diificult or inconvenient to locate the boiler at approximately the same height or elevation as the absorber as is the common a practice in most continuous absorption refrigerating units using an inert gas.

The most important advantage of this location of the vessel, however, results from the fact that absorption liquids maycirculate between the boiler and' the absorber under the influence of gravity without the use of any form of pump. The mannerin which the absorption liquid circulates, as well as other features of the operation of the unit will now be described.

In the apparatus illustrated, with the boiler above the absorber, sulphuric acid or lye solution can be used as the absorbent with water as the refrigerant. With this arrangement it is also possible to use water as the absorbent and am monia as the refrigerant. Most other absorbents and refrigerants would fall into the same category and could be used in the apparatus illustrated, the controlling condition being the specific weight of the strong and weak solution. If the strong solution is lighter than the weak solution the boiler should be located above the absorber. If the strong solution is heavier than the weak solution the boiler should be located below the absorber. Y

For purposes of illustration let us assume that the apparatus is charged with water as absorbent, ammonia as refrigerant and hydrogen as inert gas. Upon heat being supplied to the boiler B and to the auxiliary boiler 23 three main cycles of circulation will be set up.- The boiler B being at a higher temperature than the absorber A and the pre-cooling coil 33 absorption liquid will begin to circulate between the boiler and the absorber. At the start this may be due to the difference in temperature between the lower portions of the pipe 30 and 31, the pipe 30 being exposed to the atmosphere at a temperature of perhaps '75 degrees F. while the pipe 31 has a por-. tion of its length subjected to the cooling water which may be at a temperature of around 60 degrees F. As soon as absorption of.refrigerant out of the inert gas begins to take place in the absorber A, however, this circulation will be augmented due to the fact that the solution in the pipe 30 will be stronger than that in the pipe 31 and accordingly have a lower specific weight.

Accordingly gravity will act to move the liquid downwardly in the conduit 31 and upwardly in the conduit 30. As the absorption liq'uid flows across the boiler B the concentration will, of course, be decreased so that the relation of the specific weights of the absorption liquids in the conduits 30 and 31 is maintained. Experimentation has shown that the absorption liquid may be started without the use of the cooling coil 33. It has been found, however, that the solution will sometimes flow in the opposite direction to that indicated by the arrows unless the coil 33 is used. Once started it will continue to flow in that direction and so the coil 33 is not essential. Its use is desirable, however, since it insures counter-flow of liquid and gases in the absorber. The ammonia vapor expelled in the boiler B passes through the conventional cycle, flowing through the conduit 14 into the condenser C where it is liquefied and flows through the conduit 18 and 19 into the evaporator. In the evaporator the refrigerant evaporates into the inert gas and is conveyed thereby to the absorber where it is absorbed by the absorption liquid and conveyed back to the boiler B through the conduit 30. I

The third cycle within the apparatus is that of the inert gas which flows upwardly through the evaporator, thence to the absorber through the conduit 26 under the influence of the jet- J, across the absorber and back to the evaporator through the conduit 25.

It should be noted that not all of the refrigerant condensed'in the condenser C flows into the evaporator. A small portion of this condensate is conveyed by the conduit 22 into the small auxiliary boiler 23 in which it is vaporized and fed to the jet J, from which it passes into the conduit 26 which conveys it to the absorber where it is absorbed into the absorption liquid. Due to the use of the small gas separation chamber 36 there will be a local cycle of refrigerant between this vessel and the boiler 23 through the pipe 3'7 and'38 as indicated by the arrows.

Attention is also called to the fact that liquid columns form and are maintained in the conduits\ 18, 30 and 31. Due to these columns, the evaporator and the absorber operate at a slightly higher total pressure than the boiler and the condenser. Sudden changes in temperature are apt to upset the balance of the columns and care must be exercised to avoid sudden changes as much as possible. If evaporation ceases temporarily in the evaporator, the total pressure in the evaporator and the absorber is lowered and the absorption liquid level in the absorber rises and blocks off the gas circulation in conduits 25 and 26. The pipe 18 and tube 19 tend to prevent this condition from occurring by reducing fluctuations of liquid level. Other expedients, as cooling water temperature controls for the condenser or absorber, either manual or automatic? acting in response to boiler or evaporator temperature or pressure can be resorted to. Of course, if the fluids selected are such that the strong absorption liquid is heavier than the weak absorption liquid, so as to enable the boiler to be located below the absorber, the above mentioned difficulty is minimized or disappears entirely.

While only one embodiment of the invention has been shown and described'herein, it is obvious that many changes may be made without departing from the spirit of the invention or the scope of the annexed claims.

adapted to contain liquid refrigerant, means for I claim:- 1. The method of operating a continuously operating absorption apparatus consisting in expelling by heat from an absorption liquid a re-' frigerant in vaporous form, liquefying the expelled refrigerant by condensation, evaporat-' ing said condensed refrigerant by supplying heat and aborbing the vapor thereby produced by said absorption liquid, both the evaporation and the absorption occurring in the presence of a nonabsorbable gas and causing the evaporating step and absorption step to take place at a higher total pressure than that under which the expelling step and the liquefying step take place.

2. In a continuously operating absorption machine in combination an expeller suitable to contain a refrigerant. enriched absorption liquid, means for heating said expeller-to expel the refrigerant from the liquid in vaporous form, a condenser connected to said expeller and adapted to receive the expelled refrigerant and an evaporator connected to said condenser to receive the liquefied refrigerant and containing a non-absorbable gas, an absorber having two connections with said expeller to receive from it the depleted absorption liquid and to return to it refrigerant enriched absorption liquid, a conduit between said evaporator and said absorber to conduct to the latter the mixture of non-absorbable gas and vaporous refrigerant contained in said evaporator, means for cooling the absorber, said evaporator and absorber being disposed at a level below that of said expeller.

3. In a continuously operating absorption machine in combination, an expeller suitable to contain a refrigerant enrichedabsorption liquid, means for heating said expeller to expel the refrigerant from the liquid in vaporous form, a condenser connected to said expeller and adapted to receive the expelled refrigerant and having cooling means for condensing the refrigerant, an evaporator connected to said condenser to receive the liquefied refrigerant and containing a nonabsorbable gas, an absorber having two connections with said expeller to receive from it the depleted absorption liquid and to return to it refrigerant enriched absorption liquid, a conduit between said evaporator and said absorber to conduct to the latter the mixture of non-absorbable gas and vaporous refrigerant contained in said evaporator, means-for cooling the absorber, said evaporator and absorber being disposed at a level below that of said expeller, the liquid in said connections between the absorber and expeller forming columns balancing the pressure prevailing in the absorber and in the evaporator.

4. In a continuously operating absorption machine in combination an expeller suitable to contain a refrigerant-enriched absorption liquid, means for heating said expeller to expel the-refrigerant from the liquid in vaporous form, a condenser connected to said expeller and adapted to receive the expelled refrigerant and having cooling means for condensing the refrigerant, an evaporator connected to said condenser to receive the liquefied refrigerant and containing a non-absorbable gas, an absorber having two connections with said expeller: to receivegradient.

heating said auxiliary boiler, means for conducting aportion of the liquefied refrigerant into' said auxiliary boiler, a connection betweensaid aux-- iliary boiler and one of said conduits having means adapted to blow the vaporous refrigerant from said auxiliary evaporator into said conduit in the direction towards the absorber to establish mixturecirculation between the main evaporator and the absorber, means for cooling the absorber, said evaporator and absorber being disposed at a level below that of said expeller, the

liquid in said connections between the absorber and expeller forming columns balancing the pressure prevailing in the absorber and in the evaporator.

5. That improvement in the art of refrigerating through the agency of anabsorption system including a generator, an evaporator and an absorber connected to afford circulation between them and containing a plurality of complemen tary diffusing agencies in the evaporator which consists in creating a liquid column pressure head within the system, producing circulation between the generator and absorber due to said head and maintaining a lower pressure in said generator than in said evaporator due to said head by an amount determined by said head.

6, Absorption refrigerating apparatus comprising a generator, a condenser connected to said generator, an evaporator situated below said condenser, a conduit extending. vertically between said condenser and said evaporator for flow of liquid from said condenser into said evaporator, said conduit having means arranged to hold a column of liquid serving to maintain a higher pressure in said evaporator than in said condenser, an absorber connected to said evaporator, and means for circulating absorption liquid between the generator and absorber.

'7. Absorption refrigerating apparatus com-m prising a generator, a condenser connected to said generator, an evaporator situated below said condenser, a conduit extending vertically between said condenser and said evaporator for flow of liquid from said condenser into said evapora'tor, said conduit having means arranged to' hold a column of liquid serving to maintain a higher pressure insaid evaporator than' in said condenser, an absorber, means to circulate 'an auxiliary agentbetween and through the evaporator and absorber, and means to circulate absorption liquid between and throughthe generator and absorber. x

8. That improvement in the art of refrigerating through the agency of an absorption system including a generator, an evaporator and an absorber, said system containing a cooling agent and an auxiliary agent in-the presence of which the cooling agent evaporates and an absorption liquid, which consists in building up a liquid column pressure gradient and circulating said auxiliary agent between the absorber and evaporator -due to said liquid column pressure gradient and circulating said absorption liquid independently of said liquid column pressure 9. That improvement in the art of refrigerating through the agency of an absorption system including a generator, an evaporator and an absorber, said system containing a cooling agent and an auxiliary'agent into which the cooling agent evaporates, which consists in building up a liquid column pressure gradient, circulating said auxiliary agent between the absorber and evaporator due to said liquid column pressure gradient and circulating dissolved cooling agent between the generator and absorber independently of said liquid column pressure gradient.

10. In a continuous absorption refrigerating system, a boiler, an absorber located at a different level than the boiler and means for circulating absorption liquid between the boiler and absorber, said means comprising conduits having vertically extending portions adapted to contain liquids of different concentrations and specific weights as a result of changes in densityoccurring during operation of the boiler and absorber, whereby circulation is' produced by gravity action.

11. In a continuous absorption refrigerating system, a boiler, an absorber located at a different level than the boiler, means for maintaining a difference in total pressure between the boiler and the absorber and means for circulating absorption liquid between the boiler and the absorber solely under the influence of diiference of specific. gravity of liquid alone.

12. In a; continuous absorption refrigerating system, a boiler, an absorber located at a dinerent level than the boiler, means for maintaining a difference in total pressure between the boiler and the absorber and means for circulating absorption liquid between the boiler and the absorber under the influence of gravity, said last mentioned means comprising externally unheated conduits connecting the boiler and the absorber and having vertically extending portions adapted to contain liquids of difierent concentrations and specific weights as a result of changes in density occurring during operation of the boiler and absorber.

13. In a continuous absorption refrigerating system, a boiler, an absorber located at a different level than-the boiler, means for maintaining a difierence in total pressure between the boiler and the absorber and means for circulating absorption liquid between the boiler and the absorber under the influence of gravity, said last mentioned means comprising externally unheated conduits connecting the boiler and the absorber and having vertically extending portions adapted to be maintained at diiferent temperatures as heat is applied to the .boiler and removed from the absorber during operation of the unit to thereby cause the specific weights of the liquids in the vertically extending portions of said conduits to be different.

14. In a continuous absorption refrigerating system, an absorber, a boiler located above the absorber, conduits connecting the boiler and absorber, said boiler, absorber and conduits containing an absorption liquid and a refrigerant of such nature that the solution formed by the liquid and refrigerant has a lower specific weight the higher the concentration and means for changing the concentration of the solution in the boiler and in the absorber to cause the solution to circulate under the influence of gravity due to the changes in specific weight effected thereby.

15. In a continuous absorption refrigerating system, an absorber, a boiler located at a different level from the absorber, conduits connecting said boiler and absorber, said boiler, absorber and conduits containing an absorption liquid and a refrigerant forming a solution having a specific weight which changes as the concentration changes, means for lowering the concentration of the solution in the boiler and means for increasing the concentration of the solution in the absorber to cause the solution to circulate between the boiler and the absorber under the influence of gravity due to the changes in specific weight efiected thereby.

16. In a continuous absorption refrigerating system, an absorber, a boiler located at a different level from the absorber conduits, having vertically extending portions, connecting the boiler and absorber, said boiler, absorber and conduits containing an absorption liquid and means for causing the absorption liquid to circulate between the boiler and the absorber through said conduits under the influence of gravity, said last mentioned means including an arrangement for maintaining the vertically extending portions of said conduits at different temperatures whereby the liquids therein will have .dilferent specific weights.

17. A continuous absorption refrigerating system including an absorber, a generator, means for conducting an absorption liquid in a circuit between and through the absorber and the generator and an arrangement for causing circulation of the liquid over said circuit including means for adding a fluid in one part of said circuit to change the density of the liquid thereby and means for removing the added fluid in another part of said circuit to change the density of the liquid back to normal and means for causing gravity to act on the portions of different density to foster circulation.

18. The method of causing the circulation of an absorption liquid in a circuit between the absorber and the generator of a continuous absorption refrigerating system which includes the steps of causing the liquid toabsorb a gas in the absorber to thereby change the density of the absorption liquid, expelling the added gas in the generator to change the density of the liquid back to normal, and causing gravity to foster circulation of the absorption liquid due to the difference in density of the liquid in different parts of its circuit. 

